Commercial production of large scale plastic composite parts has become important in many industries including the automotive, appliance and airline industries. Significant interest lies in large structural RIM presses in which heated polymer components are mixed and reacted directly in the mold cavity. A host of other composite components such as fiberglass, graphite and the like may also be fed to the mold in addition to the desired polymeric or monomeric components in order to form the desired composite upon pressure consolidation.
Working pressure of such large scale SRIM molds can often be on the order of about 200,000 pounds. This, of course, dictates that the mold presses should be large with the vertical span of these often reaching to about 25 feet and with effective ram surface areas being on the order of 100 square feet and greater.
In many of these presses, a booking plate is detachably mounted to a moveable or ram and, in turn, one of the dies is detachably fixed to the booking plate. After the molding step, the dies are opened and then subsequently closed again so that rollers or the like on the booking plate can be received in tracks supported by the frame. Then, the booking plate and attached die are released from attachment to the ram and they can then be moved along the tracks away from their position under the ram so that the operator can gain access to the die for cleaning and other purposes. This additional mold closing step, after performance of the molding operation, adds to cycling or press down time between the actual molding steps of the cycle.
In some presses, the booking plate is pivotally mounted to the moveable ram by direct connection of hydraulic cylinders thereto, with the cylinder pistons actuating pivotal movement of the booking plates away from the moveable ram so that the press operator may gain access to the die. Direct connection of the booking plate to the pivot drive cylinders dictates that these cylinders should be generally vertically disposed, substantially parallel to the longitudinal axis of the SRIM apparatus. Addition of lengthy piston displacement along the vertical axis of these machine requires additional overhead spatial requirements, which, in many factories cannot be accommodated without removal of overhead ceilings.
Accordingly, there is a need in the art to provide a pivot drive connection for booking plates in large scale SRIM machines that minimizes overhead spatial requirements.
There is also a need in the art for a SRIM machine that may cycle quickly from molding step to next successive molding step.